Acute Rheumatic Fever
Acute rheumatic fever (ARF) is a multisystem disease resulting from an autoimmune reaction to infection with group A streptococci.
Although many parts of the body may be affected, almost all of the manifestations resolve completely.
The exception is cardiac valvular damage [rheumatic heart disease (RHD)], which may persist after the other features have disappeared.
Acute rheumatic fever (ARF) usually affects children (most commonly between 5 and 15 years) or young adults.
It remains endemic in parts of Asia, Africa and South America. It is still the most common cause of acquired heart disease in childhood and adolescence.
Pathogenesis
Organism factors- exclusively caused by infection of the upper respiratory tract with group A streptococci. Any strain of group A streptococcus has the potential to cause ARF.
Host factors- Approximately 3–6% of any population may be susceptible to ARF. Presence of familial susceptibility.
The immune response- When a susceptible host encounters a group A streptococcus, an autoimmune reaction results, which leads to damage to human tissues as a result of cross-reactivity between epitopes on the organism and the host.
Epitopes present in the cell wall, cell membrane, and the A, B, and C repeat regions of the streptococcal M protein are immunologically similar to molecules in human myosin, tropomyosin, keratin, actin, laminin, vimentin, and N-acetylglucosamine.
Antibodies developed against group A streptococcal M proteins cross react with similar proteins in human tissue (endocardium, myocardium and pericardium as well as joint and skin).
Also results in T-cell sensitization. These T cells are then recalled following subsequent exposure to group A streptococci bearing immunologically similar epitopes.
Histologically, fibrinoid degeneration is seen in the collagen of connective tissues. Aschoff nodules are pathognomonic and occur only in the heart. They are composed of multinucleated giant cells surrounded by macrophages and T lymphocytes, and are not seen until the subacute or chronic phases of rheumatic carditis.
Typically follows an episode of streptococcal pharyngitis and usually presents with fever, anorexia, lethargy and joint pains.
Symptoms characteristically occur 2-3 weeks after the initial attack of pharyngitis but the patient may not give history of sore throat.
Arthritis- The most common major manifestation and is characterised by acute, painful, asymmetric and migratory inflammation of the large joints (typically the knees, ankles, elbows and wrists). Occurs in approximately 75% of patients, usually an early feature that tends to occur when streptococcal antibody titres are high.
Carditis- a 'pancarditis' that involves the endocardium, myocardium and pericardium to varying degrees.
May manifest as breathlessness (due to heart failure or pericardial effusion),
Palpitations or chest pain (usually due to pericarditis or pancarditis).
Tachycardia, cardiac enlargement and new or changed cardiac murmurs.
Murmurs- A soft systolic murmur due to mitral regurgitation is very common. A soft mid-diastolic murmur (the Carey Coombs murmur) is typically due to valvulitis, with nodules forming on the mitral valve leaflets.
Pericarditis may cause chest pain, a pericardial friction rub and precordial tenderness.
Skin lesions- Erythema marginatum occurs in less than 5% of patients. Occur mainly on the trunk and proximal extremities but not the face.
Subcutaneous nodules occur in 5-7% of patients. They are small (0.5-2.0 cm), firm and painless, and are best felt over extensor surfaces of bone or tendons.
Appear more than 3 weeks after the onset of other manifestations and are therefore a feature that helps to confirm rather than make the diagnosis.
Sydenham's chorea (St Vitus dance)- a late neurological manifestation that typically appears at least 3 months after the episode of ARF when all the other signs may have disappeared.
Emotional lability may be the first feature and is typically followed by purposeless involuntary choreiform movements of the hands, feet or face. Spontaneous recovery usually occurs within a few months.
Other systemic manifestations are rare, but include pleurisy, pleural effusion and pneumonia.
Investigations
Evidence of a systemic illness (non-specific)
Leucocytosis, raised ESR, raised CRP
Evidence of preceding streptococcal infection (specific)
Throat swab culture: group A β-haemolytic streptococci (also from family members and contacts)
Antistreptolysin 0 antibodies (ASO titres): rising titres, or levels of > 200 U (adults) or > 300 U (children)
Evidence of carditis
Chest X-ray: cardiomegaly; pulmonary congestion
ECG: first- and rarely second-degree heart block; features of pericarditis; T-wave inversion; reduction in QRS voltages
Echocardiography: cardiac dilatation and valve abnormalities
Jones Criteria for the Diagnosis of Rheumatic Fever
Major manifestations
Carditis
Polyarthritis
Chorea
Erythema marginatum
Subcutaneous nodules
Minor manifestations Fever
Arthralgia
Previous rheumatic fever
Raised ESR or CRP
Leucocytosis
First-degree AV block (ECG changes)
PLUS Supporting evidence of preceding streptococcal infection: recent scarlet fever, raised antistreptolysin 0 or other streptococcal antibody titre, positive throat culture.
Treatment
Bed rest and supportive therapy -
Antibiotics-
Penicillin is the drug of choice and can be given orally (as penicillin, 500 mg PO twice daily for 10 days) or as a single dose of 1.2 million units IM benzathine penicillin G.
Erythromycin, 250 mg bid, may be used for patients with penicillin allergy.
Salicylates and NSAIDs- for the treatment of arthritis, arthralgia, and fever, once the diagnosis is confirmed.
Aspirin is the drug of choice. An initial dose of 80–100 mg/kg per day in children (4–8 g/d in adults) in 4–5 divided doses is often needed for the first few days up to 2 weeks.
Corticosteroids- prednisolone 1-2mg/kg per day in divided doses.
Secondary prevention-
